Neuromuscular Disease: inherited and acquired
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What components do we look at when examining for neuromuscular disorders?
• Tone (spastic, flaccid) • Power • Coordination (symmetrical?) • Reflexes • Sensation
What is a patient’s strength and reflexes like in muscle disorders (myopathy)?
• Weakness: usually proximal • Weakness > wasting • Reflexes normal (except in severely wasted muscle) • Sensory: normal
Muscular dystrophies are mostly genetic. Name examples of muscular dystrophies
• Duchenne • Becker • Myotonic • Facioscapulohumoral
Duchenne muscular dystrophy is one of the most common dystrophies, what gene is affected?
Xp21 - dystrophin gene
What is the age of onset for Duchenne muscular dystrophy?
3-5 Death usually in 20s
What are problems of Duchenne muscular dystrophy?
• proximal weakness • scoliosis, resp failure, cardiomyopathy
In Duchenne’s, why might a child’s calf look bigger than it is?
Infiltration of fat and connective tissue (not muscle)
What happens if we don’t have the distrophin molecule?
Compromise the muscle membrane integrity, results in weakness and atrophy of muscles.
What is the difference between Duchenne and Becker muscular dystrophies?
• Duchenne - frameshift deletion leads to non-functional protein • Becker - non-frameshift deletion leads to reduced function protein Symptoms for Becker are therefore less severe
Myopathies can either be genetic or acquired. Dystrophies are genetic, which pathologies are acquired?
• Inflammatory myopathies • > polymyositis, dermatomyositis, inclusion body myositis • Endocrine, GI, paraneoplastic, renal, toxic, infections, iatrogenic (steroids)
Name an inherited neuromuscular junction disorder?
Congenital myasthenic syndromes
Is myasthenia gravis acquired or inherited?
Acquired
What are reflexes and sensory function like in neuromuscular junction diseases?
Normal
What are the most common causes of neuropathies?
• Axonal neuropathies (80%) • Demyelinating neuropathies (20%)
Mononeuropathy disorders affect only one nerve. What nerve is compressed in carpal tunnel syndrome?
Median nerve
Compressing on the elbow or wrist can entrap which nerve? Also linked to handlebar neuropathy
Ulnar nerve
Which compressed nerve is responsible for foot drop?
Common peroneal nerve
What is the most common cause for metabolic polyneuropathy?
Diabetes, also renal failure as well as B12 def.
What are characteristics of Charcot-Marie-Tooth disease?
• Hereditary polyneuropathy • Common genetic neurological disorder • 1/2500 prevalence • Majority autosomal dominant • 60% have CMT1A
What is the presentation of Charcot-Marie-Tooth disease?
• Slowly progressive distal symmetrical sensorimotor polyneuropathy • Distal wasting prominent • Pes cavus
What is the orientation of the arm in Erb’s Palsy?
C5, C6 nerve roots damaged • Arm adducted • Elbow extended • Wrist pronated + flexed
What happens in radiculopathy?
Nerve root is affected -> radicular (nerve root pain) and weakness, wasting
What are common causes of radiculopathy?
Arthritis + prolapsed disc
What happens in motor neurone disease?
• Primary degeneration of motor neurones in central AND peripheral NS • Genetic or acquired • Affects lower and upper motor neurones • Affects control of all voluntary muscles except ocular + bladder • Fatal within 5 years of diagnosis